From my naive, non-lawyer point of view, a computer programming language shouldn't be copyrightable for the same reason fonts aren't -- they are the means to expression, not the expression itself. OTOH, companies have been licensing languages and APIs for years as if they were able to be copyrighted.
Moreover, can you copyright any artificial language? My instinct says “yes, but you shouldn’t”. Case in point: Loglan versus Lojban, which is somewhat analogous to the Java/J#/C# thing.
I think as soon as a language gets copyrighted, people will move away from it in droves, which would be interesting because it would enforce the idea that patents and copyrights stifle innovation rather than encourage it.
I dunno, you’ve got to strike a balance. I mean, technically I own the copyright to the compilers and interpreters I write, even if they’re under permissive licenses. But the difference between “benevolent dictator for life” and “odious stifler of innovation” is sometimes a tad unclear. It has just as much to do with public perception as the language owners themselves.